WISECO REPLACEMENT RING SET.* XR type sets consist of Top Ring, Compression Ring, and Oil Ring.* Top Ring: Alloy steel, ferrox coated, chrome faced.* Compression Ring: Cast iron, phosphate coated, taper-faced.* Oil Ring: 3-piece oil assembly; Stainless steel flex-vent spacer, chrome faced rails.* The ring type and bore size (in mm) is stamped on the dome of the piston.* Refer to this information to order the correct replacement rings.* Ring styles cannot be interchanged.* Please note: Only WISECO replacement ring sets may be used on WISECO pistons.